From Longman Dictionary of Contemporary Englishmalapropismmal‧a‧prop‧is‧m /ˈmæləprɒpɪzəm $ -prɑː-/ noun [countable] literary MISTAKEan amusing mistake that you make when you use a word that sounds similar to the word you intended to say but means something completely different
Examples from the Corpus
malapropism• In spite of his inane malapropisms, he can talk circles around everyone else in the book.• This is really a kind of malapropism.Origin malapropism (1800-1900) Mrs Malaprop character who uses words wrongly in the play The Rivals (1775) by Richard Sheridan, from French mal à propos “not appropriate” 